1. Field of the Invention
The present invention relates to a method of mounting a terminal on a printed board, a terminal mounted printed board and an electric connection box accommodating the terminal mounted printed board, which are formed by the method, and more particular, to mounting terminals at narrow pitches on front and back sides of a printed board.
2. Description of the Related Art
Some electric connection boxes mounted on an automobile use, as an internal circuit, an terminal mounted printed board having a plurality of pin terminals mounted on a printed board.
JP-A-9-186475 filed by the applicant of the present application provides an electric connection box 1 shown in FIGS. 9A, 9B. The electric connection box 1 accommodates a terminal mounted printed board 4 in a casing composed of an upper casing 2 and a lower casing 3, and all terminals 6 soldered to a printed board 5 are projected only from a surface 5a of the printed board 5 to project into a connector accommodation part 2a provided in the upper casing 2.
The terminal mounted printed board 4 in the electric connection box 1 provided by JP-A-9-186475 involves one-side mounting and so can be readily formed by reflow soldering, but involves a problem that freedom in circuit wiring is low and a board becomes large in size when a circuit pattern is complicated.
Also, JP-A-9-74261 provides a terminal mounted printed board 9, in which terminals 8 project from both front and back sides of a printed board 7 provided on both sides of a board 7a with a printed circuit 7b. When the terminals 8 project from both sides of the board 7a, reflow soldering is not possible, so that spot flow soldering is generally performed by a solder blowing nozzle. With such spot flow soldering, when a terminal 8A projecting from a front surface 7a-1 of the board 7a and a terminal 8B projecting from a back surface 7a-2 are arranged at a narrow pitch, solder H is blown against the both terminals 8A, 8B, so that the terminals 8A, 8B conduct each other. Therefore, in the case where it is necessary to insulate the terminals 8A, 8B from each other, there is a need of providing a necessary spacing between the terminals 8A, 8B, thus causing a problem that mounting at a narrow pitch is not possible and the board becomes large in size.